PURPOSE: To obtain a TbCo perpendicuarly magnetized film which has large stress inducing magnetic anisotropy by sputtering or evaporation by limiting the deposition speed of the TbCo film to within a specific range.

CONSTITUTION: The deposition speed of a TbCo film on the surface of a substrate is specified as 250/mm or more by using sputtering or evaporation for the means of forming the recording layer of an optical disk. In this case, the surface temperature of the substrate is desirable to be held at a temperature (100°C or lower) which does not almost disperse a sputtered particle or an evaporated particle on the surface of the substrate. From this point of view, the upper limit of the deposition speed is specified as 1,800/mm. Large residual stress is generated in the TbCo film by high speed film forming of 250/mm or more without the relaxation of distortion by surface diffusion causing greater stress inducing perpendicular magnetic anisotropy and the square TbCo film which has good photomagnetic characteristics can be offered stably.